This invention generally relates to analyzing electrical circuits such as wire harness assemblies. More particularly, this invention relates to a circuit analyzer arrangement having the capability of testing for one or more selected components of interest.
Circuit analyzers are used for a variety of purposes. One particular application is for testing wire harnesses to verify the integrity of a wire harness assembly. Many analyzers used for such purposes only test conductivity between expected points in the wire harness. More complicated analyzers are available to detect the presence of capacitors, resistors or diodes, for example. While such devices are available, they are typically prohibitively expensive and complicated or cumbersome to use. Moreover, the timing constraints placed on such devices renders them economically disadvantageous in a typical manufacturing concern. Accordingly, most conventionally used wire harness testing devices are not capable of detecting discrete components such as capacitors, resistors or combinations of active and passive devices within the harness assembly. As a result, each wire harness having a capacitor or other similar device typically must be manually checked using special test meters.
The conventional method of using such meters, while ultimately effective, has several shortcomings and drawbacks. The typical approach for testing a capacitor, for example, includes measuring the rise time of the capacitor. This introduces additional time during the assembly or manufacturing process, which is considered economically disadvantageous. Moreover, any resistance present within the circuit has an effect on the rise time and places constraints on the testing conditions for measuring the capacitor. Further, any stray resistance may not be accounted for while it has an adverse impact on the test results. In longer wire harness assemblies, stray resistance is a particular problem. Still further, in situations where resistors or other devices are in the wire harness assembly in combination with the capacitors, the conventional method of testing for capacitance is not capable of providing useful results.
This invention provides a significant advance in the art of analyzing a circuit or specific components within a circuit. This invention provides accurate, reliable, economical testing results while avoiding the shortcomings and drawbacks of the prior art.
In general terms, this invention is a device for testing an electrical circuit assembly having at least one component of interest. The inventive device facilitates gathering information to verify a chosen feature of the component of interest.
A device designed according to this invention includes a sample component that has a known characteristic. A test signal generator provides a pulse signal to the sample component and to the component of interest. A controller determines a relationship between an output from the sample component and an output from the component of interest. The determined relationship provides an indication regarding the component of interest so that the chosen feature of the component of interest may be verified or analyzed.
In one method according to this invention, the test signal is provided to a sample component and the component of interest when the components are in a series relationship. An output signal from each component, which in one example is a voltage across the component, is used to determine a relationship between the respective component responses to the test signal. This relationship provides information regarding the component of interest so that a desired determination can be made.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiments. The drawings that accompany the detailed description can be briefly described as follows.